Field of the Invention
The invention relates to a circuit arrangement for providing a desired DC voltage, in particular a voltage for charging a traction battery, in a vehicle. Furthermore, the invention relates to a vehicle, in particular a road automobile or a rail vehicle, comprising said circuit arrangement. In addition, the invention relates to a method of operating said circuit arrangement.
Description of Related Art
Vehicles, in particular electric land vehicles, may be provided with energy in different manners. One option is to charge an energy storage on-board the vehicle while the vehicle stops and by using an electric cable connection. According to another option, the energy is transferred to the vehicle in a wireless manner using a magnetic field which induces an electric voltage in at least one inductance on-board the vehicle. The expression “pick-up” or “receiver” has been used for the device which comprises at least one inductance. Electric vehicles may comprise a so-called traction battery. The traction battery provides electric energy to power or to propel the vehicle. The electric energy stored in the traction battery can be dissipated by an electric machine which propels the electric vehicle. It is therefore necessary to charge the traction battery in order to provide sufficient electric energy to propel the electric vehicle.
One option to charge the traction battery is to use an external source of electric energy, e.g. an external electrical network. For example, the aforementioned wireless manner uses a magnetic field to transfer electric energy from a route-sided primary winding structure to a vehicle-sided secondary winding structure, wherein an alternating voltage is induced on-board the vehicle. This alternating voltage has to be transformed such that a traction battery can be charged.
An example is described in U.S. Pat. No. 6,499,701. The document shows a circuit model for a system transferring power to an electric vehicle. An AC power signal energizes a transmission line that runs along the vehicle guideway. A ferromagnetic pick-up forms, together with the transmission line, a primary and a secondary winding, as with a conventional transformer. The AC voltage from the pick-up is rectified by a diode bridge, filtered by an inductor and a capacitor, and regulated by a buck converter so as to provide a constant DC voltage to a load.
A disadvantage of the shown solution is that significant losses are caused, in particular at a beginning of a charging procedure when a high power level is necessary. These losses can only be reduced by complex and costly circuit arrangements.
TW 201 141 006 A discloses a vehicle induction charging method including a power supply device and a power receiving device. The power supply device detects whether or not a power receiving device enters into the induction range through a first frequency-changing power supply module corresponding to a first power receiving module of the power receiving device. Furthermore, the received power and the regulated output power can be checked by a power receiving device power state data code. Since the power receiving module utilizes series connection to increase the total voltage in charging a vehicle, there is no need to use components of high-voltage specification.
US 2003/038612 A1 discloses A simple and flexible battery charger for charging high voltage battery strings includes a DC-to-AC converter that drives the primary of a transformer having multiple secondaries. Each secondary winding has a corresponding output stage formed of a rectification circuit, output inductor, and output capacitor. The output terminals of the output stages are connectable either in parallel or series.
U.S. Pat. No. 5,831,841 A discloses primary inductive path to which a high-frequency current is supplied from a power supply is laid along a guide rail for carrying car bodies and secondary electric power receiving circuit for receiving electric power from the primary inductive path in a contactless mode are disposed in the car bodies.
LU 44 443 A1 discloses a device for holding constant a voltage provided by a battery. A DC auxiliary voltage is generated via a DC converter from an output voltage of the battery, wherein the auxiliary voltage is connected in series to the output voltage of the battery.
FR 2 624 281 A discloses a stabilized power supply which has a main transformer followed by a single or multiphase rectifier and an integrator.
The document “Sebastian J. et. al., Improving Dynamic Response of Power Factor Correctors by Using Series-Switching-Post-Regulator, APEC '98, 13th Annual Applied Power Electronics Conference and Exposition, Anaheim, Calif., Febr. 15-19, 1998, New York, N.Y.: IEEE, US, 15 Feb. 1998, pages 441-446” discloses a method to improve the dynamic response of power factor correctors based on a series switching post-regulator.